1. Field of Invention
This invention relates to construction, particularly to a multi-purpose prefabricated hollow core construction which can be assembled into a plurality of shapes and configurations easily and without the need for skill, and which may be non-destructively disassembled and reassembled into other constructions.
2. Prior Art
Heretofore, different construction materials were made to fulfill the separate and discrete functions of framing, paneling, insulating, fastening, trimming, and finishing. Even though these materials originate in diverse locations, it is typical for them to be assembled in the same way, at the same location. For example, making a partition wall first requires the erection of framing with 2 inch.times.4 inch wood studs, which have to be measured, cut, fitted, and nailed. Then, usually 4 foot.times.8 foot panels, such as plasterboard or plywood, have to be fastened to both sides of the framing with nails or screws. For exterior walls, some kind of insulation material is placed between the interior and exterior panels. Interior outside corners usually require a special steel bead fixture that is nailed to the corner posts. Next, to cover up seams between panels, a special tape is applied, together with a plaster compound, over and under the tape to conceal it and make the joints smooth. The same compound has to be used over every nail or screw head that holds the paneling to the framing. They have to be carefully driven just slightly below the surface of the paneling for this purpose. Finally, panels have to be painted to cover up the patchwork and provide a uniform appearance.
All of the above--the manufacture, distribution, and use of such diverse materials--makes this kind of construction expensive. Not the least costly is the skill and labor-intensive erection and finishing process. These separate materials and the labor necessary to assemble them account for a substantial portion of the high cost of building construction.
Furthermore, these materials can be used only once: they cannot be dismantled, even if care is used, thus adding the problem and expense of demolition to building costs.
This type of construction is unnecessary and wastes natural and human resources. It would be desirable, instead, if these separate materials and the different assembly techniques they require were integrated into one adaptable, reusable material.
To be cost-effective, temporary, rigid structures, such as in-plant or on-site offices, must be built in factories using similar conventional labor-intensive building methods as described above. Consequently, they are not collapsible and portable, like a tent, but are transportable only, usually on wheels. Rather than suit the needs of the end user, they must be shaped for the ride--long, narrow (sometimes in halves), and low, to fit on flatbed trucks, which must travel on roads and under overpasses. Also, once built, they cannot easily be rearranged or supplemented. It would be desirable if such temporary structures could be shipped collapsed, could be easily assembled on site by unskilled workers, and were capable of being rearranged and supplemented.
Moreover, the very same physical property--chemical inertness--of many of these manufacturing materials that make them useful also prevents them from biodegrading in the environment. Recycling is only a partial solution to this dilemma because of separation and collection problems. And these materials lose their desirable properties with repeated recycling. It would be desirable if products made with these materials were capable of repeated use, each use lasting as long as possible before recycling.
There are many industries, such as packing and crating, where materials, because they are not adaptable, must be destroyed in use, thus becoming waste after only one use. It would be desirable if materials used in such industries were adaptable to multiple uses.
Two-sided corrugated cardboard, for example, is widely used for packaging in this wasteful way. This material (and now its newer plastic equivalent) is limited to manufacture of boxes with relatively thin-walled outer shells. The very structure that makes them useful must be collapsed by scoring (crushing) to permit folding. This makes boxes weak and vulnerable, particularly at corners, where they require reinforcement, and turns them into trash after only one use. Thicker versions, which are either glued thin layers, or the honeycomb type, are too thick to be scored for folding. This limits their use to merely filling the interiors of conventionally framed hollow partition walls, and certain esoteric uses, such as light-duty interior displays. These uses typically require extremely labor-intensive design and fabrication methods--mainly because the exposed edges of these materials are so rough, unsightly, and easily damaged that they need finishing and protection. One method for doing this requires panels of these materials to be inserted into specially prepared frames. Another method requires the core portions of panel edges to be crushed to make room for protective strips, usually of wood, which are then fixed in place along the edges. The problem is, these frames and strips must themselves be measured, cut, mitred, assembled, glued, and finished.
The above-described problems and limitations are also true of the various foam-filled panel materials that are available.
Nondestructive universal adaptability and re-use would be desirable in such industries as convention exhibits, theatrical and window displays, office and home partitions, knock-down furniture, sheds and animal shelters, storage buildings, etc.
Standardization of parts has been the primary way of attempting to compensate for the lack of true universal adaptability. Such parts are typical of user-assembled prefabricated construction. They cannot be adjusted for size; only selected from stock. For example, prefabricated partition or display systems, in order to offer a choice of arrangements to users, typically provide different connector elements, or posts. One is used in the corner to make two-wall, L-shaped connections; another is used in three-wall, T-shaped connections; and yet another to make four-wall, X-shaped ones. These connectors are used with standard-size modular panels, which determine the spacing between the connectors. The problems with such systems are: users must have just the right kind and number of parts for each use, must accept and make-do with standard, fixed panel sizes, and the resultant uniformity. It would be desirable if partitions and displays could be assembled to any configuration and any size with a single material that integrally combines connector and panel parts.
Prefabricated picture framing is a good example of the above mentioned problem with standard sizes. The standard size frames have a serious limitation: most pictures do no come in standard sizes. The framing public wants to frame pictures of random size, but for that the choice is limited; thus expensive custom framing or section-type frames must be used.
Available in pre-mitred strips which are sold in pairs, the section frame enjoys continued sales in spite of serious problems because it attempts to emulate custom framing. It does this by offering a choice of section lengths, generally from 8" to 40".
The problems associated with section frames, however, are formidable. Dealers must stock 33 different section sizes multiplied by the number of stock units per size, constantly check inventory and reorder popular sizes. This requires an extraordinary commitment of dealer attention and store space, and because of this they tend not to replenish stock of less frequently used sizes. Also, there is no room left for a good choice of colors. The public is bored with aluminum, the most commonly available color by far. And frame colors that are available scratch and chip easily because the color is usually only on the surface. Thousands of potential dealers cannot and will not make such a commitment, even though they do want to sell frames.
Furthermore, a most important marketing advantage is lost to the section frame: impulse purchasing. Customers must know the exact picture size at the time of purchase, which means they must measure and plan in advance. Like other fixed size devices, the section frame is not adaptable. Thus, it must either be used as is, or it must be stored or thrown away. In short, it is too much trouble, requires too much skill, and is not enough fun for most people.
Fun, of course, is the purpose of construction toy sets. Usually, they are comprised of separate structural and connector elements, each in quantity, that are combined in different ways. Because of all the different kind and number of parts such sets contain, the parts are easily and frequently lost, causing the set to gradually "disappear". And they are usually bulky and expensive. A construction toy with a small number of separate parts which, nevertheless, can be assembled into a large number of configurations would be desirable. Such a toy would not only appeal to children, and adults with children in mind, but evoke an adults own playful desire for assembly.
Attempts have been made to solve some of the above problems, but these have all had one or more serious drawbacks:
Olszewski, in U.S. Pat. No. 2,643,745 (1953) shows hinged-together two-part, male-female locking elements which are stored separated and rolled up. They can be interlocked while unrolling to form a rigid, straight pole for emergency use by fire departments, and the like. However, the erected pole is uni-directional. There is no interest in, or provision for construction perpendicular to the direction of the erected pole. Furthermore, there is a contradiction between rigidity of the erected pole and how easily the elements slidably fit together. The necessary tolerances in manufacture that enable slidable assembly of the elements add up and increase as the pole is lengthened, giving a flaccid, rather than a rigid result.
Lerchenthal, in U.S. Pat. No. 3,537,223 (1970) shows various interlocking concrete building (compression) elements that are externally reinforced (tensioned) with steel sheets. These, too, can be rolled up. Provision for right angle construction, however, is not integral; adapter elements are needed. Furthermore, the integration of compression/tension forces necessary for structural reliability are solely dependent upon adequate adhesive bonding of the steel sheets to the concrete elements, and is thus subject to failure.
Wrigley, in U.S. Pat. No. 4,573,296 (1986) shows an interlocking method for forming hollow-core panels out of two sheets of formable material. Once formed, however, his panels cannot be adapted to other shapes.
Walter, in U.S. Pat. No. 3,975,882 (1976) shows hollow panels that can be interlocked to form rigid, curved panels. The radius of curvature depends upon which panel combination is selected. These, too, can be rolled up for storage. However, there is no way to form angular corners.
Mentken, in U.S. Pat. No. 3,883,975 (1975) [applicant's patent] shows flexibly connected elements intended for adaptable picture framing. Elements are in contact when arranged in a straight line, forming a rigid member. Removable corner pieces permit right angle construction, but in one direction only. Furthermore, rigidity is less than optimum because there is not enough mass in the direction of stress, and no internal rigidity-producing interlocking compression/tension.
Valenzano, in U.S. Pat. Nos. 3,992,834 (1976) and 4,550,543 (1985), and Mackenroth, in U.S. Pat. No. 4,099,887 (1978) are merely tenon and mortise variants whereby tenons and mortises are prefabricated to have angles. Different angled pairs can be selected and slidably assembled to form structures. Pairs having 45-degree angles can be assembled to be either straight or 90-degrees, depending on how they are oriented prior to slidably assembly. The lengths between joints or corners can only be changed by selecting new lengths from stock. Valenzano offers a greater variety of angle alternatives, bu they both suffer from the same contradictions: To be adequately rigid and leakproof, they must have tight-fitting, strong joints. If their joints are adequately tight and leakproof, they are also more difficult to slidably take apart and reassemble. Raised beads on sliding surfaces reduce friction, but such joints require caulking to make them leakproof. Furthermore, these types of joints depend on adequate mass around them for strength, not compression versus tension. Therefore, strength can only be increased with a corresponding increase in weight.
Thomson, in U.S. Pat. No. 3,596,396 (1971) shows cubes hinged to enable them to be rearranged in a few different groupings as an amusement only. Apart from their connecting hinges, they only contact, but do not fasten to one another.